Syutheses of the Major Metabolites of (2E,4E,6E,8E)- and (22,4E,6E,8E)-3,7-Dimethyl-9-(2,6,6-Trimethyl-1-Cyclohexen-1-YL)-2,4,6,8-Nonatetraenoic Acids (Retinoic Acid and 13-cis-Retinoic Acid)

Abstract

Wittig condensation of (2E,4E)-[5-(3-oxo-2,6,6-trimethyl-1-cyclohexen-1-yl)-3-methyl-2,4-pentadienyl]triphenylphosphonium bromide with ethyl formylcrotonate or 4-hydroxy-3-nethylbutenolide gives, respectively, the (all-E) and (22,4Z)-3,7-dimethyl-9-(2,6,6-trimethyl-3-oxo-1-cyclohexen-1-yl)-2,4,6,8-nonatetraenoic acids. These are converted to oxo and hydroxy metabolites of retinoic acid and 13-cis-retinoic acid.